DistributedPulseModulation

Distributed pulse modulation done like with the old P82C150, but with descrete components

Theory of operation

With a regular Pulse Width Modulation (PWM), all the pulses are grouped in a same and unique pulse over the whole period. On Distributed Pulse Modulation (DPM) and Dyadic Descrete Pulse Modulation (DDPM), the aim is to distribute all the "sub-pulses" throughout the whole period.

Two advantages :

• spectrum with more high frequencies than PWM : easier filtering in case of A/D conversion
• as the pulse distribution is continuously evaluated : a threshold modification, before the period end, is taken into account without delay

Old P82C150 for DPM implementation

P82C150 - Application note

P82C150 datasheet

DDPM implementation based on Paolo S. Crovetti thesis

Thèse : Paolo S. Crovetti

The breakout board

Features

PWM (Pulse Width Modulation)
DPM P82C150-like (Distributed Pulse Modulation)
DDPM (Dyadic Discrete Pulse Modulation)

Photographies done with the PCB_V1.0 board

MCP23017 Port A & B

MCP23017 is an I2C 16bits IO expander
Port A & B are used to control the board
Prescaler decoding values :
0x00	1
0x01	2
0x02	8
0x03	16
0x04	64
0x05	256
0x06	1024
0x07	4096

Board configurations (PCB_V2.0)

PWM

• do not populate the CD74HCT4053
• place the jumpers as describe in the silkscreen schematic (PWM)

DPM

• do not populate the CD74HCT4053
• place the jumpers as describe in the silkscreen schematic (DPM/DDPM)

DDPM

• do not populate the 74LS85
• place the jumpers as describe in the silkscreen schematic (DPM/DDPM)